Earthing in kitchen

[Alan]

I have just removed a cupboard in my kitchen. I found a thickish earth cable just coming out of the plaster but not connected to anything. I am guessing that it was intended to be some sort of bonding to the cold water supply which enters near by - but the cable is just not quite long enough to be connected to the copper water pipe. There is a junction box near by, which appears to be part of the ring main - it has a spur going off to a power socket above the work surface. Should I extend the earth cable and connect it to the incoming water supply; should I also connect it to the earth on the ring main, or do something else, or do nothing.

[Bod]

You should run a separate 9mm earthing cable from the cold mains pipe all the way back to the main earth on the consumer unit.

[Brian Gaff]

I'd have thought bonding all three would cover most issues. IE the cable in the wall is an unknown source, but is obviously earthed, so earthling it agaiwon't hurt.

Brian

[John Rumm]

First is there already an main equipotential bond to the cold water supply elsewhere? If there is, then you can ignore this spare one.

Second if the main bond is missing, is this one suitable? i.e. thick enough[1], and does it go back to the main earthing terminal?

[1]

If it turns out its required and usable, then yes you can connect it to the pipe. Ideally it should be shortly after the main stopcock in the house. Really it should be an unbroken run of wire, but soldering or crimping an extension would next best.

Lastly there is no requirement for supplementary bonding in a kitchen, so don't connect it to the CPC of the ring circuit.

[Alan]

Thanks - also Bod and Brian. I think I will make a job of it and run a totally new earth back to the main earthing terminal just be be certain.

[RobertL]

Surely, for equipotential bonding, the pipes coming into the wet room need to be electrically bonded together but not to anything else.

Robert

[RobertL]

I also hestitate to mention, but for a kitchen don't you need to be part P approved to do any electrical work?

Robert

[Robin]

I took "cold water supply which enters near by" to mean the supply to the property, not just to the kitchen, but I could well be wrong.

And a kitchen used to be a "special location" but the changes to Part P from April 2013 mean it isn't now.

(under "What is not notifiable).

[Alan]

So are you suggesting that I cannot run an earth cable from the kitchen to the garage: connecting one end to the copper pipe and the other end to the main earthing terminal myself?

[Tim Watts]

Got a feeling that bonding is notifiable - unless that changed in the last round of revisions...

So it being a kitchen may be moot...

[Chris French]

No, AIUI bonding isn't notifiable (and never was) - seems confirmed by a read of Part P and a quick web search.

Anyway, even if it was notifiable, and say just get on and do it anyway. no one is going to know or care,

A general note to Robert and Alan, you don't need to be 'approved' to do any electrical work. All Part P requires is that certain work (new circuit, new CU, work in special location - bathroom, sauna) is notified to the Local Authority.

[ARW]

Does anyone sell 9mm earth cable?

[ARW]

Soldering or crimping is classed as unbroken.

Yep

[ARW]

Yes. And that was true even when the bonding was in the kitcken and the kitchen used to be a special location.

[Bod]

10mm.

[Cursitor Doom]

[...]

Earthing a metal kitchen sink as they do is a daft idea. Suppose I accidentally stick my fingers in a live light socket whilst leaning on the sink with my other hand? What might have been a slight tingle with an unearthed sink could now easily kill me as I get the full 230V across me. And if the sink is wet, my skin resistance goes close to zero and I get blown to pieces; they'll have to recover my body parts from the neighbours' gardens. Let metal sinks float, I say. Far safer.

[Syd Rumpo]

No, not easily. It's really very, very rare.

Cheers

[Cursitor Doom]

If it's true that it's "really very, very rare" then I'd venture to say that when people claim they've had a belt off the mains and survived, in most cases they've probably not had the *full* whack due to the protection afforded by footware/carpets/lino etc. IOW, they're not sufficiently earthed to get the full effect. But in the circumstances I suggest, where you're fully earthed and the current flows between your hands - across your chest - there's plenty enough mils there to stop your heart - even if your hands are dry.

[Tim Watts]

Yes - I just found a better reference...

[polygonum]

But there is a fair chance that a sink will already be earthed sufficiently well, e.g. by copper pipe, to give you the full 230V, or very close. Your argument, if valid, should lead to a requirement for sinks to be installed with plastic pipework, etc.